250rwkw + RB20det HOW 2

[GTS-t VSPEC]

Personlly I would suggest finding a turbo specialist and discuss with them what your requirements, in terms of performance, are. They should be able to custom make a turbo to any specs you want.

There are alot of bad t3/t4 turbo's , so do some shopping around.

See'ya:burnout:

[BOOSTMEISTER]

To be honest most of the rb20 housings (EXH) will be cracked, all the ones I have seen have been so sourcing another one is better. The turbo for Lukes car cost around the $1800 mark but we did source a number of parts and this did include a new oil feed and machined manifold

[BOOSTMEISTER]

The other thing is that this turbo is laggy nothin till 4000 then hold on to ya hat Ma, it all happens rather speedily

[Arron Sutton]

What boost was he running to make this power and what rpm is he making full boost?

[BOOSTMEISTER]

He has run up to 22psi with the stock internals I think full boost is around 6300 with redline at 8500

[sn00p]

whatsisname - What mods do you have to your rb25 to get 257kw and what are the specs of your turbo?

Thanks BEn

[Sydneykid]

Hi snOOp, our RB25DET gets 260 rwkw, it has....

GCG hi flowed RB25DET turbo (at 1.3 bar)

Tomei cams 256 degrees (inlet works with VVT)

Jun adjustable exhaust pulley

Cat back HKS exhaust

Split pulse dump

HKS intercooler and pipework

Power FC

Z32 AFM

Jamex panel filter in standard box

Custom fabricated aluminium inlet from AFM to turbo

Did 12.5 for 1/4 at Willowbank just before Xmas in a full weight, manual R34 GTt.

Hope that helps

[Sydneykid]

Hi guys, I am surprised by the lack of use of simple mathematics sometimes, particularly when talking about turbo spool up.

It is pretty simple really, say we pick 3 common RB engines with the same turbo and assume the same engine efficiency. The capacity is the main thing that determines the rpm at which the engine develops boost. The following table assumes the same compression ratio and efficiency in all 3 engines.........

Engine CC's Boost RPM

RB20DET 1,998 3,600

RB25DET 2,476 2,900

RB30DET 2,964 1,950

Simply put, an RB25DET is 24% bigger in capacity than a RB20DET. Therefore it will produce the same amount of exhaust, spin the turbo and develop boost 24% lower in the rev range. Ditto an RB30DET is 48% bigger in capacity than a RB20DET. Therefore it will develop boost 48% lower in the rev range.

If you want to allow for compression ratio, a good rule of thumb is to simply factor in the difference in compression ratio eg; if in the above example the RB20DET had a 8.5 to 1 compression ratio and the RB25DET had a 9.0 to 1 compression ratio, the RB25DET would have boost at 2,750 rpm (instead of 2,900 rpm).

This is not perfect, but it is a good rule of thumb and in the real world is pretty close to the mark.

Another rule of thumb we use is a performance engine should not develop boost until at least 1/3 of the available RPM is used. Otherwise the turbo is too small.

So if we assume that our 3 X RB engines above all rev to 7,500 rpm, then 1/3 is 2,500 rpm. So the turbo would be too small if used on the RB30DET as it develops boost at 1,950 rpm. It could be said that the turbo is too big for an RB20DET as it develops boost at 3,600 rpm (a long way from 2,500 rpm). At 2,900 rpm (or 2,750 rpm with 9.0 to 1 compression ratio), the RB25DET would seem to be a pretty good fit for this turbo.

Hope that makes sense

[meggala]

cam great results as always aren't you getting the turbo bug again

good to see you back one the forums great result for for the set up I'm considering a simialr one for my cefiro I have injectors and z32 afm so we will see.

btw all you people saying rb 20 are tough I have popped 2 in the last 18 months cant be thart tough bu tstill a good motor

cheers

meggala

[EVOIV]

Having said that the RB20 is a strong engine, the SR20 is also just as strong if not stronger. Has anyone read of that white JUN s15 tuned here in Australia that has put out a stupid 600 or more horsepower at the wheels!?? Of course it runs a 2.2L stroker kit with TRUST T88...but still, that thing will go